Adipose Derived Stem Cells Exert Immunomodulatory Effects on Natural Killer Cells in Breast Cancer

Objective: Adipose derived stem cells (ASCs), as one of the important stromal cells in the tumor microenvironment, are determined with immunomodulatory effects. The principle aim of this study was to evaluate the immunosuppressive effects of ASCs on natural killer (NK) cells. Materials and Methods: In this experimental study, we assessed the expressions of indolamine 2, 3-dioxygenase (IDO1), IDO2 and human leukocyte antigen-G5 (HLA-G5) in ASCs isolated from breast cancer patients with different stages as well as normal individuals, using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). Immunomodulatory effects of ASCs on the expression of CD16, CD56, CD69, NKG2D, NKp30, NKG2A and NKp44 was also assessed in peripheral blood lymphocytes (PBLs) by flow-cytometry. Results: Our result showed that IDO1, IDO2 and HLA-G5 had higher mRNA expressions in ASCs isolated from breast cancer patients than those from normal individuals (P > 0.05). mRNA expression of these molecules were higher in ASCs isolated from breast cancer patients with stage III tumors than those with stage II. The indirect culture of ASCs isolated from breast cancer patients and normal individuals with activated PBLs significantly reduced NKG2D+ and CD69+ NK cells (P < 0.05). Conclusion: Results of the present study suggest more evidences for the immunosuppression of ASCs on NK cells, providing conditions in favor of tumor immune evasion.